Exhaust conduit for aircraft and cooling system therefor



Jan. 14, 1941. 2,228,637

EXHAUST CONDUIT FOR AIRCRAFT AND COOLING .SYSTEM THEREFOR P. E. MERCIER V`1938 2 Sheets-Sheet 2 Filed March' ATTORNEY@ Patented Jan. 14, 1941.:

PATENT OFFICE EXHAUST CONDUIT FOR AIRCRAFT `AND COOLING SYSTEM THEREFOR .Perrevllirnest Mercier, Paris, France Application March23, 1938, Serial No. 197,584 In France December 24, 1937 `5 claim. e (orso-31) This invention relates to exhaust conduits for aircraft engines and cooling systems therefor, and

has`forV its object to providemeanswhich will tend Ato ensure ilame suppression at the level of l the exhaust. y I I n According Lto the invention the exhaust gases are brought into contact with a cooling 'medium along a predetermined surface obtained by a particular formation of the exhaust conduit.; The

exhaust-conduit may -have a widened vportion combined with a flattened portlonv,-whe`reby the cross-section available forthe' ow of exhaust gases is maintained constantor increases slightly towards the outlet end of the exhaust conduit.

` x In order that the gases will ow to the lexterior of the cowling and will be discharged inthe direction of the thin streams of air travelling along the cowling, the conduit also comprises, in a planek cowling, to other parts of the enginewhichare at lower temperature and which alsorequire'cooling. t.. so Theparticular form of 'the exhaust vpipe according to the above feature of the invention may advantageously he combined with ascirculatio'n of cooling air peculiar to the exhaust conduit or conduits disposed, if necessary, in a special compartment, the outlet for the said cooling air being disposed below the outlet lip of the exhaust conduit according to the invention with the ob- 'ject of withholding the exhaust gases from the layer of cooling air.

In the accompanying drawings,

Figure 1 shows diagrammatically and in longitudinal section a cowling having a return circulation of the cooling air and embodying the in- 4 vention, and

YFigure 2 shows, in perspective, the exhaust pipe included in Figure 1. i

Figure 3 is a section on line 3-3 in Figure 1. 50 Figure 4 is a diagrammatic view of the cylinder and deflectors of the apparatus in section as taken on line 4-4 of Figure 1, while Figure 5 is also a section of Figure 1 on line 5-5 when the construction is modified so that 55 the lips I8 join to form a continuous slot if the surface of the cowling by the interposition of this.

associated engine is assumed to have nine cylinders.A

Throughout the views the same reference numbers indicate sameor corresponding parts.l

In Figure 1, the nose piece of the engine', is 6 shownon the left.` One cylinder of the engine is indicated at I and is provided with cooling fins and deectors 2` which guide the cooling air through the ns and cause this air to be dis charged'towards the cylinder head 3 provided 10 with a` deilector 4. -The partitioning is such that cooling air entering at 5 is guided inthe direction of the arrows shown in the drawings, 'its direction of circulation being reversed after it has cooled the cylinders, so that the thin streams of airfescape'through `a. slot 6 stuated'near the front of the engine after having traversed the cylinder head. i

One lof the rocker rods is shown at 'Land the casing of the admission rocker at 8, though these 20 members are not essential to the understanding of the invention. The exhaust conduit is shown at 9, and is arranged in a jacket Il), which terminates on the right with a flared mouth as shown, and is closed at` I I by an annular partition fitted on the vconduit 9. The piping which complet'es the jacket is shown' at I2. The deilector' 4 combined with the outerwall I3 of the cowling separates two zones;V under different pressures.

Thus, between the spaces I4 and I5 situated in the, two zones there is a rdifference .of pressure which is due to the arrangement of the cowling and ensures the passage of thev air over the iins of Athe cylinder'head 3, that is to say, from right to left in the figure. l'Ihis pressure dierence ensures the ow of air through the jacket I 0 and the conduit I2 connected thereto.

The exhaust conduit 9 has an extension I6 connected thereto by a bail joint I1 and leading to 40 the atmosphere at I8 after having described two bends Vof Lopposite direction I9 and 20. The extension I6 is disposed in acompartment 2 I ,which may-be annular, for example in the case of a radial engine, and is fed. with cooling air through a feed slot 22. A baiile plate 23 causes the air to pass under the extension I6 and then to leave in sheet form at 24 under the lower outlet lip of the pipe I8. A sleeve 25 of truncated'cone shape. separates the extension I6 from the space I4 con- 50 taining the cooling air of the engine.

Figure 2 is a diagrammatic representation of the exhaust pipe. 'I'he outlet IBis curved in a. manner corresponding to that of the adjacent part of the cowling. The whole is suspended on flattening, the directionof this longitudinal axis at the outlet of the pipeV causing the exhaust gases the spars 21, which constitute part of the frame of the aircraft.

Figures 1 and 2 of the accompanying drawings show, by way of example, the application of the invention to a cylinder head which is cooled by a current of air flowing in the opposite direction to that of the exhaust gases flowing out through the exhaust conduit. This is the case, for example. with the Cowling forming the subject of the Patent No. 2,206,417 issued on July 2, 1940, the exhaust conduits being situated behind the engine. In this type of cowling difficulties mayiarise due to the fact that the air for cooling the cylinder head must flrst pass over the exhaust conduits. Even when the exhaust conduitszare disposed in a separate compartment, which is advisable, the cooling of the exhaust conduits in the neighborhoodof the cylinder heads is a difiloult problem which, however, is met by the arrangements according to the invention.

The sectional and diagrammatic views shown in Figures 3 and 4 illustrate the position of the defiectors 2 and 4 in relation to the engine. v

It will be understood that it is possible without departing from vthe invention, f or example,to couple together the exhaust pipesof adjacent cylinders. and if necessary to combine their outlet apertures so as to form a continuous aperture on the surface of the-cowling, i Y

An example of such construction is illustrated in the modification of Figure 5,v which while being drawn as a section oil-Figure 1 nevertheless reveals the feature of having the lips I8 join to form a continuous slot for an associated engine having nine cylinders.

What I claim as my `invention and desirejtok Vsecure by Letters Patent of the United States is:

1,. In an aircraft engine provided with an exhaust pipe lodged with a cowling, the feature of having the cross-section of said exhaust pipe progressively flattened as it extends from-the cylinder towards the outletend whilst the longi-l. tudinal axis of the conduit describes two succes-` sive opposite bends in a plane perpendicular to that of the said flattening, the direction of lthis l longitudinal axis at the outletend of the pipe causing the exhaust gases to escape substantially parallel to the exterior surface, of said cowling,

and means for passing a current of ,air between said outlet and said Cowling.

2. In an aircraft engine provided with an exhaust pipe lodged with a cowling, the feature of having the -cross-section of said exhaust pipel progressively flattened as it extends` from the cylinder towards the outlet end, this flattened secto escape substantially parallel to the exterior surface of said cowling, and means for passing a current of air between said outlet and said cowling.

3. kIn anfaircraft engine provided with an exhaust conduit, the feature of having the crosssection of said exhaust conduit flattened progressively as it extends from the cylinder towards theoutlet end ofthe pipe, this section increasing slightly towards the 'said outlet, while the longitudinal axis of the conduit describes two successive oppositebends injarplane perpendicular to that-of the saidilattening, the direction of this axisat the outlet end bf the conduit causing the exhaust gases to escape substantially parallel to the exterior surface of said cowling, and means for-passing a current of air between said outlet and said cowling.

4. In` an aircraft provided with an engine, an inwardly curved cowling therefor, and an exhaust A pipe, the feature which consists in having the cross-section of -the exhaust .pipe progressively flattenedgas it. extends frmthe engine cylinder towards the-outlet end of the conduit, while the longitudinal axis of theA conduit describes `two successive opposite bends in a plane perpendicularto `Vthat ofthe said-flattening, the direction of a this loxigituciinal axis at the outlet end'of.V the conduit causingthegses of, theengine to escape outlet opening-being in the form of an inwardly curved slot whosecurvature corresponds to that of the said cowling.

5. man aircraft provided with a 'multi-cylinder.

engine, and an exhaust conduit for each cylinder and a cowling, for said enginathe feature of having thel cross-section of the conduit ofj each ,.7 cylinder progressively fiattened `as it extendsl from the cylinderrtowards theoutlet end of the conduit whose longitudinal axis describes two suev cessive opposite bends in a plane perpendicular to that of the said flattening, the direction of this longitudinal axis at the outlet end of the conduit l causing the exhaust gases to escape substantially parallel to the exterior surface of said cowling,

- and means for passing a current of air between said outlet and said cowling, the outlet openings. of the several exhaust conduits having the form of inwardly curved'slots which are combined into the 'form of a continuous annularslot for-'thelk PIERRE-'ERNEST MERCIER.. i 'f 

